Remarkable Improvement in Hydrogen Sensing Characteristics with Pt/TiO₂ Interface Control

Area of Science:

• Materials Science
• Chemical Sensing
• Nanotechnology

Background:

• Titanium dioxide (TiO2) thin films are promising for hydrogen sensing due to surface susceptibility.
• Existing TiO2 sensors require high temperatures (150-400 °C) and exhibit poor room-temperature performance.
• Electrode fabrication is a critical, yet underexplored, factor influencing sensor surface and performance.

Purpose of the Study:

• To investigate the impact of electrode fabrication on TiO2 thin film sensor performance.
• To develop a highly sensitive and selective room-temperature hydrogen sensor.
• To elucidate the sensing mechanism behind the enhanced performance.

Main Methods:

• Fabrication of TiO2 thin film sensors with optimized electrode conditions.
• Characterization using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).
• Electrical transport measurements to determine interface barriers and thermal activation energy.

Main Results:

• Optimized sensors achieved a high response (SR ∼ 1.58 × 10^7) to 10,000 ppm H2 at room temperature.
• Excellent linearity (R-square ∼ 0.98) was observed for H2 concentrations from 300-10,000 ppm.
• High selectivity factors (SF) were demonstrated against interfering gases (CH4, CO, NH3) and humidity at room temperature and 100 °C.

Conclusions:

• Electrode fabrication critically influences TiO2 sensor surface properties and performance.
• The optimized sensor exhibits superior room-temperature hydrogen detection capabilities.
• Sensing mechanisms are explained by grain size, atomic composition, Pt/TiO2 interface barriers, and intergranular barrier heights.